Toothed rack in the U.S.?

Question

Toothed rack in the U.S.?

hcpe (Mechanical)

(OP)

22 Aug 03 10:22

I have to specify a toothed rack and I only have a few dimensions. In ISO we have a module m (measured in millimetres) and a pitch p measured in millimetres. But what do you do in the U.S. and where can I find some information (i.e. about standard sizes), which will make me able to specify the rack?
(The pitch is approx. 20 mm (0.787 in) and the tooth height is 13.2 mm (0.52 in) and the top flat face is 4,50 mm (0,177 in)

Best regards

Mikkel Krogh

diamondjim (Mechanical) · Answer 1 · 2003-08-22 10:55:12

Normally for a full depth tooth
you can use 2.25 divided by the
dimetral pitch for the tooth depth.
If it is a stub tooth form, the
rack would be 2.00 divided by the
diametral pitch for the tooth depth.
I assume it is a 4 dp gear or 6.35
module.
The 4 diametral pitch would result
in a .7854 inch pitch or 19.949mm.
I did not check the tooth thickness
at the tip to determine the pressure
angle.
You can use the standard millimeter
proportions and use the 6.35 module
to determine the tooth proportions.
It is unlikely but possible that the
addendum might be shaved or have
a truncation. If it is a stubbed
tooth form, use .8 times the module
for the addendum and 1.0 times the
module for the dedendum.

EnglishMuffin (Mechanical) · Answer 2 · 2003-08-22 18:00:25

Also, you might find this helpful :

http://www.stdsteel.com/gear.htm

hcpe (Mechanical) · Answer 3 · 2003-08-27 06:51:30

Thank you for the answer! it was a great help.

Best regards
Mikkel

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Toothed rack in the U.S.?